1. Field of the Invention
The present invention relates to an uninterrupted power supply apparatus, and more particularly, to an uninterrupted power supply apparatus which is capable of charging to a backup battery as the public electrical power distribution system is supplying power.
2. Description of Related Art
A conventional uninterrupted power supply apparatus by applying double boost converter 1, as shown in FIG. 1, utilizes two sets of boost converters 10, 12 to perform boosting voltages and power factor correction in a public electrical power supply mode. Herein, the two sets of boost converters 10, 12 receive a positive half-cycle of voltage potential VP and a negative half-cycle of voltage potential VN from a rectifying unit 14 respectively, perform boosting voltage and power factor correction for the positive half-cycle of voltage potential VP and the negative half-cycle of voltage potential VN alternatively and successively, and convert outputs to a first output voltage Vo1 and a second output voltage V02. The two sets converters 10, 12, transfer the first output voltage Vo1 and the second output voltage Vo2 alternatively and successively to a current shunt 16, meanwhile, the current shunt 16 may shunt the first output voltage Vo1 and the second output voltage Vo2 and allow an AC output power Vac to pass.
Again, referring to FIG. 1, the uninterrupted power supply apparatus by applying double boost converters 1 functions in the public electrical power supply mode, a backup battery applied can not perform charging in the circuitry Moreover, even though the backup battery is not in function, the backup battery 11 itself may perform self-discharging, thereby resulting in running out of power sometimes. Because the conventional uninterrupted power supply apparatus by applying double boost converters 1 itself doesn't provide a charger, the backup battery 11 used which is required must be charged by an external charger. As a result, the conventional uninterrupted power supply apparatus by applying double boost converters 1 often need to design an additional charger module (not shown) individually, so as to charge the backup battery 11, thereby increasing manufacturing cost, causing inconvenience of use, and increasing defect rate for electronic products.